In communication systems, and more specifically, cellular radiotelephone systems, frequency hopping is used to increase subscriber capacity by reducing overall system interference. One such frequency hopping technique, fast-synthesizer frequency hopping, is useful to realize small increases in subscriber capacity. Fast-synthesizer frequency hopping allows a single transmitter to hop over an arbitrary number of frequencies. To provide multiple carriers in a cell (i.e., an increase in subscriber capacity), signals transmitted at a transmitter's output are combined utilizing wideband hybrid combiners. Unfortunately, these wideband hybrid combiners provide at least 3 dB of loss per stage of combining. Consequently, power loss of a signal transmitted by a transmitter increases with the number of channels provided.
Another frequency hopping technique used for high capacity applications is baseband frequency hopping. Baseband frequency hopping is useful to realize large increase in subscriber capacity. In baseband frequency hopping, fixed-frequency transmitters (i.e., transmitters that do not fast-synthesizer frequency hop) are interconnected to antennas through frequency-selective cavities to achieve low-loss combining of signals transmitted by the transmitters. Frequency hopping is achieved by distributing baseband information to all the transmitters with appropriate synchronization. Unfortunately, the number of hopping frequencies is limited to the number of fixed-frequency transmitters employed.
Thus, a need exists for an economical means to hop over a number of frequencies to yield a mid-range subscriber capacity increase, yet still mitigate power loss of a signal transmitted.